We can simplify \((\sqrt{0.7} + \sqrt{70})^{2}\) by expanding the square of the binomial:

\((\sqrt{0.7} + \sqrt{70})^{2} = (\sqrt{0.7})^{2} + 2(\sqrt{0.7})(\sqrt{70}) + (\sqrt{70})^{2}\)

Simplifying each term, we get:

\(0.7 + 2(\sqrt{0.7 \times 70}) + 70 = 0.7 + 2(\sqrt{49}) + 70 = 0.7 + 14 + 70 = 84.7\)

So the simplified expression is 84.7.